Production of fast dyeings



' Patented a. 18, 1927.

UNITED STATES PATENT. OFFICE.

FRITZ PETERHAUSER, OF RIEHEN, NEAR BASEL, SWITZERLAND, ASSIGNOR TO'THEFIRM DURAN!) & HUGUENIN S. A., OF BASEL, SWITZERLAND.

PRODUCTIQN on FAST DYEINGS.

No Drawing. Application filed March 12, 1925, Serial No. 15,136, and inGermany March 20, 1924.

According to U. S. Letters Patent application Ser; No. 653,567, filedJuly 24, 1923, fast dyeings are produced on fibres or other substrata byimpregnating the latter with solutions of ester salts of vat dyestufi's,such as are obtained according to the process of U. S. Letters PatentNo. 1,448,251, and by develo ing afterwards the dyeing, by way ofreormation of the parent vat dyestufi, with the assistance of a suitableoxidizing agent. In above mentioned Letters Patent-a plication Ser-. No.653,567, it has been state that these ester salts have for the most partno afiinity to the materialto be dyed. With reference to the animalfibre, this statement has been modified as in the same Letters Patentapplication further down it has been mentioned that these ester saltsfii themselves on the animal fibre from a weak acid bath and at a highertemperature.

It has now further been found that vari-- ous cellulosic fibres,especially cotton, mercerized cotton, viscose and the like acquireanpessentiall enhanced receptivity. for these estersalts w en there isadded to the dyebath a salt which is capable of lessening the solubilityof the ester-salt in water and thus increases the proportion of theester-salt taken up b the fibre, so that in the subsequent deve opmentin the oxidation bath, much dee' er d eings can be obtained than withoutt is a dition of salt, a fact which greatly enhances the dyeing. Saltswhich are suitable for this purpose are for example common salt, Glaubersalt etc.

The im roved process may be explained by the fol owing example:

In a bath containing 6.6 gm. of the'sodium salt of the leuco indigosulphuric acid ester, obtained according to Example I of said U. S.Letters Patent No. 1448,251, 6.6 grs. of nitrite and 33 s. of Gllaubersalt, viscose is impregnate at ordinary temperature .dye bath.

been added as in the case of t e first bath.

Then rinse and dry. Thus a deep dyeing fast to rubbing is obtained,which is much deeper than the one which could have been obtained withoutthe addition of salt to the Instead of viscose, cottonor mercerizedcotton can be dyed in the same way.

The effect of this addition of salt seems to vary on the differentfibres. On viscose the efiect is especially stron On weavings withdifferent threads an the like, dyeing efi'ects of difierent intensitycan also be pro duced according to .this process.

Obviousl the oxidation will be efiected in a secon bath with ironchloride, nitrite and sulphuric acid etc. as stated in the cited U. S.Letters Patent application Ser.

What I claim is:

1. A process for producing fastdyeings by means of'ester salts ofvat-dyestufis resulting from their leuco-com ound polybasic acid esters,consisting in adding to the dye bath a solubilit lessening salt capableof increasing the a sorption power of the fibre for the vat dyestufiester salts, for the pur pose of producing deeper dyeings.

2. A process for producing fast dyeings by means of ester salts ofvat-dyestufis resulting from their 1eucjo-compound polybasic .80 acidesters, consisting in adding Glauber salt .to the dye bath so as toincrease the absorption power'of the fibre for the vat-dyestufl' estersalts, for the purpose of producing deeper dyeings.

- In witness whereof I have hereunto signed my name this 28th da ofFebruary, 1925.

FRITZ ETERHAUSER.

